Programmable or non-programmable computer apparatus to control operating events in vehicles and engines therefor are well known, for example from the W. German Pat. No. 2,504,843 (to which U.S. Pat. No. 4,063,539 corresponds), the W. German published application DE-OS No. 25 39 113 and the W. German published application DE-OS No. 2,655,948 (to which U.S. Pat. No. 4,174,688 corresponds). Such computers, having many components, have complex structures and hence are subject to a variety of possibilities for error. An error which, in itself, is insignificant can nevertheless lead to the breakdown of the system to be controlled, and can immobilize the internal combustion engine, or the vehicle driven by the engine.